Solid state steerable light

ABSTRACT

A light assembly and method for steering a vehicle headlight illumination pattern. In one aspect, a method includes providing a processor programmed to perform the steps of: illuminating a subset of consecutive LEDs in the line including LEDs associated with the first and second edge illumination fields; as the direction of the vehicle wheels changes: (i) fading the LED associated with one of the first and second illumination fields off while simultaneously fading the LED associated with the other of the first and second illumination fields on thereby changing the illumination pattern; and (ii) repeating step (i) so that the illumination pattern tracks the direction of the vehicle wheels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/371,958, filed on Dec. 7, 2016, which is a divisional ofU.S. patent application Ser. No. 14/885,052, now U.S. Pat. No.10,427,591, filed Oct. 16, 2015, which is a divisional of U.S. patentapplication Ser. No. 13/342,573, now U.S. Pat. No. 9,162,611, filed onJan. 3, 2012, each of which is incorporated herein by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to steerable or adaptive lightingassemblies and more specifically to solid state adaptive assemblies fordirecting light to different locations without physically movinglighting components.

Conventional headlights on a vehicle generate a light pattern that isdirected forward to light the space in front of the vehicle duringforward motion and work well when a vehicle is traveling along astraight line in the forward direction. The lighting profile in thesecases often has a relatively bright light spot in the center of a widerlight pattern to illuminate a long distance directly in front of thevehicle where a driver's line of sight is most often directed. When avehicle is turning, a driver's line of sight is typically along thedirection of the turn and therefore not aligned with the bright lightspot in the center of the wider light pattern. Thus, while the brightspot is useful when the vehicle is travelling directly forward, thebright spot does not enhance a driver's ability to perceive danger whenexecuting a turn.

Some headlights have been developed that include steerable lightingmodules where a bright spot can be swiveled left or right to align withthe direction of vehicle travel when a vehicle is travelling directlyforward or when the vehicle is turning. For instance, some lights havebeen developed that include light modules that are mounted for rotationabout a vertical axis through a range that enables the modules to directlight patterns generally along directions selected by a vehicle steeringsystem. Thus, when a steering system turns to the left, the lightmodules are rotated to the left to a similar degree and when thesteering system turns to the right, the light modules are rotated to theright to a similar degree.

Lights having mechanically rotating modules have two shortcomings.First, these systems require several moving parts and therefore arerelatively expensive to implement. Second, because these systems includemoving mechanical parts, they often require more maintenance than aconventional headlight and therefore are more expensive to maintain.

Some solid state steerable headlights have been developed that addressthe problems related to mechanically rotating modules. For instance, itis known to provide a one or two dimensional array of LEDs where theLEDs generate separate adjacent light fields and where different subsetsof the LEDs may be illuminated to generate light patterns at differentlocations in front of a vehicle. For instance, in a simple exampleincluding fifteen LEDs in a row from left to right, where the firstthree LEDs to the left are on and the others are off, the light patternwould appear generally to the left, where the last three LEDs to theright are on and the others are off, the light pattern would appeargenerally to the right, and other pattern locations between the far leftand far right locations would result from turning on other subsets ofLEDs with the balance of the LEDs off.

While solid state steerable lights may be less costly to manufacture andhave fewer maintenance problems than lights including mechanicallyrotatable modules, solid state lights also have several shortcomings.First, as well known in the LED lighting arts, even when LEDs aremounted closely to each other, there are dark spots between adjacentLEDs that result in dark spots or lines between the illumination fieldsgenerated by adjacent LEDs where the illumination level is noticeablylower than within the illumination fields. Dark lines in an illuminationpattern are annoying to drivers, especially during turns where the darklines are moving with respect to a scene being viewed by the driverduring execution of a turn.

Second, as LEDs in an array are turned on and off to simulate mechanicalrotation of a light module during a turn, the turning on and off actionof the LEDs is relatively abrupt so that a driver perceives thedifferent LED illumination fields being turned on and off in a stepwisefashion. Here, while the illumination pattern is clearly moving, themovement is stepped as opposed to being smooth and is often annoying toa driver.

BRIEF SUMMARY OF THE INVENTION

It has been recognized that two or more light modules can be providedwhere each module includes a separate array or bank of LEDs and wherethe modules are arranged so that illumination fields of the LEDs in thedifferent modules overlap such the dark lines between illuminationfields associated with adjacent LEDs in one array are illuminated byillumination fields generated by LEDs in at least one of the otherarrays. In this manner, the annoying dark lines associated with priorLED based steerable headlights are eliminated.

It has also been recognized that during the process of steering anillumination pattern from one position or trajectory to another positionor trajectory, the illusion of smooth movement of the illuminationpattern can be enhanced by changing the duty cycles of LEDs in acontrolled fashion. For example, the duty cycles of LEDs can becontrolled so that light intensity along an edge of the resultingillumination pattern in the direction of pattern movement increasesgradually while light intensity along an edge of the pattern in thedirection opposite pattern movement decreases gradually. In thisfashion, the perceived stepped changes in light pattern perceived inprior light systems can be substantially eliminated.

Consistent with the comments above, at least some embodiments of thepresent invention include a light assembly for generating a lightpattern, the assembly comprising a first light module including a firstLED array and a first lens, the first LED array including at least afirst line of LEDs where each LED in the first array generates an LEDlight pattern and where dark areas occur between adjacent LED lightpatterns, the first lens arranged adjacent the first LED array toproject light from the first LED array forming a first light patternincluding interleaved bright and dark areas corresponding to the LEDlight patterns and dark areas between the light patterns that areassociated with the first LED array and a second light module includinga second LED array and a second lens, the second LED array including atleast a second line of LEDs where each LED in the second array generatesan LED light pattern and where dark areas occur between adjacent LEDlight patterns, the second lens arranged adjacent the second LED arrayto project light from the second LED array forming a second lightpattern including interleaved bright and dark areas corresponding to theLED light patterns and dark areas between the light patterns that areassociated with the second LED array, wherein the first and second lightmodules are arranged with the first light pattern misaligned with thesecond light pattern so that at least a subset of the bright areas inthe first light pattern are aligned with dark areas in the second lightpattern to generate a combined light pattern.

In some cases the system further includes a processor for controllingthe LEDs in the first and second LED arrays, the processor receiving acontrol signal and using the control signal to turn LEDs in the firstand second arrays on and off to adjust the angles of light projected bythe first and second lenses. In some cases the processor controls theLEDs in the first LED array differently than the processor controls theLEDs in the second LED array. In some cases no more than three LEDs inthe first and second LED arrays are on at one time. In some cases thesystem further includes a processor for controlling the LEDs in thefirst and second LED arrays, the processor receiving a control signaland using the control signal to adjust intensity of the LEDs in thefirst and second arrays to adjust the direction of the combined lightpattern emanating from the lenses.

In some embodiments the processor controls intensity of the LEDs via apulse width modulation process. In some cases at least one LED in atleast one of the first and second LED arrays is driven at a maximumintensity at all times. In some cases when at least one LED in one ofthe first and second LED arrays is driven with a high intensity togenerate a relatively high intensity area in the combined pattern, LEDsin the other of the first and second LED arrays that illuminate areas inthe combined pattern on either side of the high intensity area aredriven with a lower intensity that is lower than the high intensity togenerate lower intensity areas adjacent the high intensity areas in thecombined pattern.

In some embodiments the combined light pattern can be adjusted within arange of positions from a first position wherein a single LED at a firstend of each of the first and second light modules is driven with a highintensity and at least a subset of the other LEDs in the light modulesare off and a last position wherein a single LED at a second end of eachof the first and second light modules is driven with a high intensityand at least a subset of the other LEDs in the light modules are off. Insome cases when the combined light pattern is at a position between thefirst and last positions, only a subset of the LEDs in each light moduleis on and at least a subset of the LEDs that are on are driven with aduty cycle that is less than a maximum duty cycle.

In some embodiments no more than three LEDs in the first and secondlight modules are driven at any time. In some embodiments only one LEDin the first and second light modules is driven at a maximum duty cycleand only two LEDs in the first and second light modules are driven atless than the maximum duty cycle. In some cases the two LEDs that aredriven at less than the maximum duty cycle generate illumination fieldsthat at least partially overlap the illumination fields generated by theLED that is driven at the maximum duty cycle.

In some embodiments the assembly is a first assembly and the combinedlight pattern is a first combined light pattern and where the firstassembly is for use with a second assembly to form a pair of headlightson a vehicle wherein the second assembly generates a second combinedlight pattern that mirrors the first combined light pattern, the firstand second assemblies arranged so that the first and second combinedlight patterns are substantially aligned and combine to generate aheadlight pattern. In some cases the LED lines are substantiallyhorizontal and wherein the first and second light modules form aheadlight for a vehicle. In some cases the LED lines are substantiallyvertical and wherein the first and second light modules form a light foruse on a lift truck. In some embodiments each of the first and secondlines of LEDs includes first through fifth LEDs and wherein theprocessor controls the intensities of each LED.

Other embodiments include a light assembly for generating a lightpattern, the assembly comprising a first light module including a firstLED array and a first lens, the first LED array including at least afirst line of LEDs where each LED in the first array generates an LEDlight pattern, the first lens arranged adjacent the first LED array toproject light from the first LED array forming a first light patternincluding separate adjacent illumination fields corresponding to eachLED in the first LED array and a second light module including a secondLED array and a second lens, the second LED array including at least asecond line of LEDs where each LED in the second array generates an LEDlight pattern, the second lens arranged adjacent the second LED array toproject light from the second LED array forming a second light patternincluding separate adjacent illumination fields corresponding to eachLED in the second LED array, wherein the first and second light modulesare arranged with the first light pattern misaligned with the secondlight pattern so that at least a subset of the illumination fields inthe first light pattern overlap at least two illumination fields in thesecond light pattern to generate a combined light pattern.

In some embodiments the first and second light modules are arranged withthe first and second light patterns misaligned so that at least oneillumination field in the first light pattern overlaps each two adjacentillumination fields in the second light pattern and at least oneillumination field in the second light pattern overlaps each twoadjacent illumination fields in the first light pattern.

Yet other embodiments include a light assembly for generating a lightpattern, the assembly comprising a plurality of LEDs mounted in a line,at least a first lens positioned in front of the LEDs to direct lightfrom each LED into an illumination field associated with the LED whereinthe illumination fields of energized LEDs together create anillumination pattern and wherein a first edge illumination field is atone end of the illumination pattern and a second edge illumination fieldis at another end of the illumination pattern opposite the one end and aprocessor controlling the LED duty cycles to move the illuminationpattern projected by the at least a first lens in a first direction tothe side of the first edge illumination field opposite the second edgeillumination field by (i) increasing the duty cycle of an LED associatedwith the first edge illumination field while simultaneously decreasingthe duty cycle of an LED associated with the second edge illuminationfield until the duty cycles of the LEDs associated with the first andsecond edge illumination fields are maximum and minimum duty cycles,respectively and (ii) repeating step (i) with the illumination fieldadjacent the first edge illumination field in the first direction as thefirst edge illumination field and with the illumination field adjacentthe second edge illumination field in the first direction as the secondedge illumination field the maximum and minimum duty cycles are 100% and0% duty cycles at least one LED is driven with 100% duty cycle at anytime only three LEDs in the plurality of LEDs are driven at a non-zeroduty cycle at any time.

In some embodiments the processor is also for controlling the LED dutycycles to move the illumination pattern projected by the lens in asecond direction to the side of the second edge illumination fieldopposite the first edge illumination field by (iii) increasing the dutycycle of an LED associated with the second edge illumination field whilesimultaneously decreasing the duty cycle of an LED associated with thefirst edge illumination field until the duty cycles of the LEDsassociated with the second and first edge illumination fields aremaximum and minimum duty cycles, respectively and (iv) repeating step(iii) with the illumination field adjacent the second edge illuminationfield in the second direction as the second edge illumination field andwith the illumination field adjacent the first edge illumination fieldin the second direction as the first edge illumination field.

In some cases the plurality of LEDs includes first and second banks ofLEDs arranged in a line and wherein the at least a first lens includesfirst and second lenses where the first lens is positioned in front ofthe first bank of LEDs to direct light from each LED in the first bankinto an illumination field associated with the LED and the second lensis positioned in front of the second bank of LEDs to direct light fromeach LED in the second bank into an illumination field associated withthe LED wherein the illumination fields of energized LEDs in the firstand second banks together create the illumination pattern and wherein aseparate illumination field associated with the first bank LEDs overlapseach two adjacent illumination fields associated with the second bankwhile a separate illumination field associated with the second bank LEDsoverlaps each two adjacent illumination fields associated with the firstbank. In some embodiments no more than two LEDs in the first and secondLED banks are driven at partial duty cycles at one time.

Some embodiments include a method for smoothly moving a light patternacross a space, the method for use with a plurality of LEDs mounted in aline and at least a first lens positioned in front of the LEDs to directlight from each LED into an illumination field associated with the LEDwherein the illumination fields of energized LEDs together create anillumination pattern and wherein a first edge illumination field is atone end of the illumination pattern and a second edge illumination fieldis at another end of the illumination pattern opposite the one end, themethod comprising the steps of providing a processor programmed toperform the steps of, controlling LED duty cycles to move theillumination pattern projected by the at least a first lens in a firstdirection to the side of the first edge illumination field opposite thesecond edge illumination field by (i) increasing the duty cycle of anLED associated with the first edge illumination field whilesimultaneously decreasing the duty cycle of an LED associated with thesecond edge illumination field until the duty cycles of the LEDsassociated with the first and second edge illumination fields aremaximum and minimum duty cycles, respectively, and (ii) repeating step(i) with the illumination field adjacent the first edge illuminationfield in the first direction as the first edge illumination field andwith the illumination field adjacent the second edge illumination fieldin the first direction as the second edge illumination field.

Other embodiments include a method for steering a vehicle headlightillumination pattern wherein a headlight includes a plurality of LEDsarranged in a line and at least a first lens mounted adjacent the LEDsto direct light from each LED into an illumination field associated withthe LED, wherein the illumination fields of energized LEDs togethercreate an illumination pattern and wherein a first edge illuminationfield is at one end of the illumination pattern and a second edgeillumination field is at another end of the illumination patternopposite the one end, the method comprising the steps of providing aprocessor programmed to perform the steps of, illuminating a subset ofconsecutive LEDs in the line including LEDs associated with the firstand second edge illumination fields, as the direction of vehicle wheelschanges (i) fading the LED associated with one of the first and secondillumination fields off while simultaneously fading the LED associatedwith the other of the first and second illumination fields on therebychanging the illumination pattern and (ii) repeating step (i) so thatthe illumination pattern tracks the direction of the vehicle wheels.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described. The followingdescription and the annexed drawings set forth in detail certainillustrative aspects of the invention. However, these aspects areindicative of but a few of the various ways in which the principles ofthe invention can be employed. Other aspects, advantages and novelfeatures of the invention will become apparent from the followingdetailed description of the invention when considered in conjunctionwith the drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a top plan view of a vehicle in a right lane of a road andshows an illumination pattern generated by vehicle headlights;

FIG. 2 is similar to FIG. 1, albeit showing a vehicle turning about aright-hand curve and a different illumination pattern in front of thevehicle;

FIG. 3 is a perspective view of a headlight that is consistent with atleast some aspects of the present invention;

FIG. 4(a) is a partially exploded view showing lenses and LED banks thatform first and second light modules of FIG. 3;

FIG. 4(b) is a partial cross-sectional view showing the lenses and LEDbanks of FIG. 4(a) as well as a virtual location of a seventh LED in theLED banks relative to the first LED bank;

FIG. 5(a) is a schematic illustrating the exemplary light modules ofFIG. 4(b) and illumination fields corresponding to each of the LEDs inthe light modules;

FIG. 5(b) is a graph illustrating an illumination pattern profile thatmay be generated by the light modules in FIG. 5(a);

FIG. 6 is a schematic illustrating two headlights like the headlightshown in FIG. 3 and a resulting illumination pattern;

FIG. 7 is a schematic illustrating a control system for the LEDs in thelight modules of FIG. 4;

FIG. 8(a) is a schematic illustrating illumination pattern positionindicators as well as LED duty cycle boxes and resulting illuminationfields where the illumination pattern position is set to position 2.29within a range between zero and eight;

FIG. 8(b) is a graph illustrating an illumination pattern profile thatresults from the duty cycle shown in FIG. 8(a);

FIG. 9(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 8;

FIG. 9(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 8;

FIG. 10(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 7.7;

FIG. 10(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 7.7;

FIG. 11(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 7.4;

FIG. 11(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 7.4;

FIG. 12(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 7.0;

FIG. 12(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 7.0;

FIG. 13(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 1.4;

FIG. 13(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 1.4;

FIG. 14(a) is similar to FIG. 8(a), albeit with the illumination patternposition set to position 0;

FIG. 14(b) is similar to FIG. 8(b), albeit with the illumination patternposition set to position 0;

FIG. 15 is similar to FIG. 8(a), albeit showing light modules arrangedvertically and resulting illumination fields;

FIG. 16(a) is a graph illustrating an exemplary wide illuminationpattern profile with a dark spot formed by the profile where the darkspot can be steered within the wider illumination pattern;

FIG. 16(b) shows a wide bright illumination pattern similar to FIG.16(a) albeit without a dark spot;

FIG. 17 is a schematic diagram similar to FIG. 5(a), albeit showing fourlight modules arranged in a horizontal line and resulting illuminationfields; and

FIG. 18 is a schematic diagram illustrating first and second lightmodules and resulting fields where each light module includes three rowsof five LEDs.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals correspondto similar elements throughout the several views and, more specifically,referring to FIG. 1, a top plan view of a vehicle 11 traveling within alane 12 on a road is illustrated where the vehicle 11 is traveling in adirection indicated by arrow 14. Vehicle 11 includes two headlights 18that generate light forming a light pattern identified by numeral 16.

Referring to FIG. 2, in general the disclosure describes an adaptive orsteerable headlight system for a vehicle 11 where, as the vehicle 11 isturning about a curve, the light pattern (see 16 a in FIG. 2) adjusts oris steered to provide additional light to illuminate the area towardwhich the vehicle is traveling. Thus, for instance, in FIG. 2 where thefront steering tires 30 of vehicle 11 are directed about a curve 20 inlane 12, (see arrow 14 that shows the direction of tires 30), headlights18 are controlled to generate light pattern 16 a that illuminates thearea to which vehicle 11 is traveling.

Referring now to FIG. 3, an exemplary headlight 18 that has featuresconsistent with at least some aspects of the present invention isillustrated. Among other components, headlight 18 includes a steerablelight assembly 40 that in turn includes, among other components, a firstlight module and a second light module 44. Referring also to FIG. 4(a),first light module 42 includes a bank 48 of five LEDs labeled 1, 2, 3, 4and 5 which are mounted in a line to a PCB board 46 and an asphericallens 52. LEDs 1-5 generate light which travels away from the mountingsurface of PCB 46. Lens 52 is mounted adjacent board 46 such that lightgenerated by LEDs 1-5 is directed through lens 52.

Referring also to FIG. 4(b), a central axis through lens 52 is labeled61. LEDs 1 through 5 are spaced apart minimally and form a line whereLED 3 is central to the line. The LED bank 48 is offset by an offsetdistance −Δ to one side (e.g., left as illustrated in FIG. 4(b)) ofcentral axis 61 where −Δ is approximately ¼ the distance between centralaxis (not labeled) through adjacent LEDs. Light from LEDs to either sideof central LED 3 is redirected by lens 52 to travel along trajectoriesthat pass generally through a central plane defined by central axis 61.To this end, see phantom light trajectories 54 and 55 corresponding toLEDs 1 and 5 that veers toward and eventually through the plane definedby axis 61. Light from central LED 3 is also redirectly, albeitslightly, so that at least a portion travels across central axis 61.Referring also to FIG. 5(a), the end result is that LEDs 1-5 generateadjacent illumination fields F1-F5 as illustrated, and that form a firstlight pattern.

Referring still to FIGS. 4(a) and 4(b), second light module 44 includesa bank 50 of five LEDs labeled 6, 7, 8, 9, and 10 which are also mountedin a line to PCB board 46 and an aspherical lens 54. LEDs 6-10 generatelight which travels away from the mounting surface of PCB 46. Lens 54 ismounted adjacent board 46 such that light generated by LEDs 6-10 isdirected through lens 54. A central axis through lens 54 is labeled 63.LEDs 6-10 are spaced apart minimally and form a line where LED 8 iscentral to the line. The LED bank 50 is offset by an offset distance +Δto one side (e.g., right is illustrated in FIG. 4(b)) of central axis 63where +Δ is approximately ¼ the distance between central axis (notlabeled) through adjacent LEDs. Light from LEDs to either side ofcentral LED 8 is redirected by lens 54 to travel along trajectories thatpass generally through a central plane defined by central axis 63. Tothis end, see the phantom light trajectories 57 and 59 correspondingLEDs 6 and 10, respectively, that veers toward and eventually throughthe plane defined by axis 63. Light from central LED 8 is alsoredirected, albeit slightly so that at least a portion travels acrosscentral axis 63. Referring also to FIG. 5(a), the end result is thatLEDs 6-10 generate adjacent illumination fields F6-F10 as illustrated,and that form a second light pattern.

Referring once again to FIG. 4(b), the slight offsets −Δ and +Δ resultin an offset between the fields generated by the first and second banksof LEDs 48 and 50, respectively. More specifically, as shown in FIG.5(a) where the +Δ and −Δ values are approximately ¼ the distance betweencentral axis through adjacent LEDs, the offset is approximately ½ thewidth of one of the illumination fields. In FIG. 5(a), fields F1-F5 areshown vertically offset from fields F6-F10 in order to simplify thisunderstanding. In practice, it at least some applications, fields F1-F5are vertically aligned with fields F6-F10. As shown in FIG. 5(a), eachspace between adjacent fields corresponding to the first bank of LEDs1-5 is illuminated by a field associated with one of the LEDs in bank 50and, similarly, each space between fields associated with adjacent LEDsin bank 50 is illuminated by one of the illumination fields associatedwith one of the LEDs in bank 48 as the first and second light patternscombine to form a combined light pattern.

Referring still FIG. 5(a), it has been recognized that different subsetsof the LEDs 1-10 can be energized to generate different overall lightpatterns within the space associated with fields F1-F10. Morespecifically, by exciting different subsets of LEDs 1-10, the pattern oflight generated thereby can be effectively steered to the left or rightor to the center. For instance, as shown in FIG. 5(a), when LEDs 2, 3and 7 are illuminated (see projected light 72 (top-to-bottom hatch), 74(left-to-right hatch) and 76 (cross-hatch)) while the other LEDs 1, 4-6and 8-10 are off, only fields F2, F7 and F3 are illuminated and hencethe resulting illumination pattern is offset to the right of a centerline 69 as illustrated. See also FIG. 5(b) that shows illuminationpattern resulting when LEDs 2, 3 and 7 are illuminated to a maximumlevel (i.e., at a 100% duty cycle) while the balance of LEDs in module42 and 44 are turned off.

Pattern 80 a is offset to the right of center line 69. Pattern 80 a hasa stepped profile because side portions of pattern 80 a are onlyilluminated by light generated by one of the LEDs (e.g., either LED 2 orLED 3) while the center portion includes overlapping light generated byLED 7 and one or the other of LEDs 2 and 3. By changing which three ofthe LEDs 1-10 are on at any time, the resulting pattern 80 a can bemoved to the left or right as indicated by the phantom arrow 82 shown inFIG. 5(b). By stepping the on and off activity in a controlled fashion,movement of illumination pattern 80 a can be controlled so that it has arelatively smooth appearance. For example, referring still to FIGS. 5(a)and 5(b), to move pattern 80 a to the right, LED 3 may be turned off todarken field F3 at the same time that LED 6 is turned on to illuminatefield F6. To move another step to the right, LED 7 may be turned off todarken field F7 while at the same time turning on LED 1 to illuminatefield F1.

Referring still to FIG. 5(b), by providing a pattern 80 a that has alower intensity at the sides and a higher intensity at a middle portion,the resulting illumination pattern looks as though it is fading out orfading in at its edges as the pattern is moved from left to right orvice versa, thereby further enhancing the smooth moving affect observedby a person driving the vehicle 11.

Referring now to FIG. 6, in at least some embodiments the light pattern80 a generated by a second headlight 18 is identical to and completelyaligned with the light pattern 80 a generated by the other headlight 18such that the intensity of the combined pattern is twice the intensityof pattern 80 a.

Referring now to FIG. 7, a system 100 for controlling the first andsecond light banks 48 and 50, respectively, of one of the headlights 18is illustrated. The system 100 includes a processor 102, a sensor 101, apower source 106, LED switches 104, a power bus 108 and switch linescollectively identified by numeral 110. Processor 102 performs variousprocesses that are consistent with at least some aspects of the presentinvention. To this end, processor 102 is linked to sensor 101 as well asto LED switches 104. Sensor 101 is a steering sensor that, as the labelimplies, senses direction in which wheels 30 are headed. Sensor 101generates a direction signal which is provided to processor 102.

Referring still to FIG. 7, power source 106 is, in the illustratedembodiment, a 700 milliamp, 4 volt max power source that providesvoltage on bus 108. Bus 108 is connected to the anode of each of theLEDs 1-10. The LED switches block 104 includes 10 separate LED switches,each of the switches linked to a cathode of a separate one of the LEDs1-10. Each switch in block 104 is linked to processor 102 such that theprocessor 102 can turn any subset of the switches on or off therebyproviding power to one or a subset of the LEDs 1-10.

Referring still to FIG. 7 and also again to FIGS. 5(a) and 5(b), inoperation, as the driver of a vehicle turns a steering wheel to turntires 30, the direction signal from sensor 101 is provided to processor102. Processor 102 uses the direction signal to determine who the LEDs1-10 should be energized to cause the resulting illumination pattern tobe directed along the direction of travel of the vehicle. Processor 102then controls switches 104 to cause the illumination pattern to steeraccordingly. Again, because the patterns from the first and second LEDbanks 84 and 50 are interleaved, and because the pattern is less intensealong side portions thereof as best shown in FIG. 5(b), as processor 102controls the switches 104 to move the pattern left or right, the patternappears to move relatively smoothly which has a nice visual appearance.

It has been recognized that, in addition interleaving illuminationpatterns from adjacent light modules and generating a light pattern thatis less intense along side portions than in a central area, the illusionof smooth movement of a pattern can be enhanced by adjusting the dutycycles of LEDs during the light steering process. To this end, referringnow to FIG. 8(a), modules 42 and 44 are again shown along withillumination fields F1-F10 corresponding to LEDs 1-10, respectively. Inaddition, a position slider icon 120 is shown along with a positionvalue block 122, a first subset of LED duty cycle blocks 124 and asecond subset of LED duty blocks 126. In the illustrated example,position slider icon 120 can be slid horizontally along the illustratedslider bar to any position from the left end to the right end asillustrated and represents the control command from sensor 101 (seeagain FIG. 7) indicating the direction in which the steering tires 20 ofa vehicle 11 (see again FIG. 2) are pointed and hence the direction inwhich the lighting pattern generated by the LEDs 1-10 should bedirected.

In the illustrated example, the range of positions is between a zeroposition at the left of the slider bar as illustrated and an 8 positionat the right of the slider bar. Block 122 indicates a current positionof the position slider icon 120 and in the illustrated example shown inFIG. 8(a), the current position is 2.29 (out of 8). The first duty cycleblock 124 includes five duty cycles boxes, a separate box for each oneof the LEDs 1-5 in the first LED bank 48. Each duty cycle box is labeledwith a number that corresponds to an associated one of the LEDs 105.Thus, a second box which is labeled 2 corresponds to the LED labeled 2in bank 48, the third box which is labeled 3 corresponds to the LEDlabeled 3 in bank 48, etc. Each duty cycle box includes a percentagevalue between 0% and 100% and indicates the duty cycle used to drive anassociated LED when the position shown by slider 120 and indicated inblock 122 is selected. Thus, for instance, duty cycle box 2 includes a71% duty cycle in FIG. 8(a) indicating that associated LED 2 is drivenwith a 71% duty cycle when position 2.29 is selected. Similarly, dutycycle box 3 includes a 29% duty cycle indicating that LED 3 in drivenwith a 29% duty cycle when position 2.29 is selected. As shown, whenposition 2.29 is selected, in the illustrated example, LEDs 1, 4 and 5are completely off because duty cycles boxes 1, 4 and 5 have a zeropercent value.

The second subset 126 of LED duty cycle blocks include boxes 6-10corresponding to LEDs 6-10, respectively, in LED bank 50. Each dutycycle box 6-10 indicates the duty cycle used to drive an associated oneof the LEDs 6-10 in LED bank 50 given the position indicated by icon 120and block 122. In the illustrated example, duty cycle box 7 indicates a100% duty cycle meaning that LED 7 is driven to a maximum intensitywhile boxes 6, 8, 9 and 10 indicated that the associated LEDs 6, 8, 9and 10 are off when position 2.29 is selected. Duty cycles arecontrolled by PWM switching by processor 102 as well known in the art.

Referring still to FIG. 8(a), as in FIG. 5(a) above, when LEDs 2, 3 and7 are illuminated, the resulting illumination fields F2, F3 and F7 aregenerated where fields F2 and F3 are adjacent each other and field F7 isdirected toward a space centered on the dark space between fields F2 andF3 so that field F7 generally equally overlaps fields F2 and F3. Here,because each of the LEDs 2, 3 and 7 is driven with a different dutycycle, each of the separate fields has a different intensity. In theillustrate example, consistent with the description of the first andsecond subsets of duty cycle blocks above, fields F2, F3 and F7 haveintensity values of 71%, 29% and 100%, respectively. Because fields F2,F3 and F7 overlap as shown, the combined intensities result in fourdifferent intensity areas across the width of the illumination pattern.In this regard, see FIG. 8(b) where profile 80 b of the illuminationpattern is shown. Referring to FIGS. 8(a) and (b), the illuminationpattern 80 b has a 29% intensity value in the lateral left quarter (i.e.in a first edge illumination field), 129% intensity value in the centerleft quarter (i.e., the combination of the 29% intensity from LED 3 and100% intensity from LED 7), a 171% intensity value in the center rightquarter (i.e., the 71% intensity value from LED 2 combined with the 100%intensity value from LED 7), and a 71° A intensity value in the lateralright quarter (i.e., in a second edge illumination field). Thus, theresulting illumination pattern 80 b, while still relatively intense in acenter area, fades off along lateral edges more appreciably than pattern80 a shown in FIG. 5(b) where LEDs are simply on or off.

Referring still to FIG. 8(a) as the position indicated in block 122 ischanged, the duty cycles corresponding to LEDs 1-10 are also changed. Ingeneral, in the present example, at any position within the rangebetween positions 0 and 8, either one LED in each of LED banks 48 and 50is driven at a 100% duty cycle or one of the LEDs in one of the banks 48and 50 is driven within a 100% duty cycle while two of the LEDs in theother of the banks 48 and 50 are driven with partial duty cycles wherethe partial duty cycles add up to a 100% duty cycle. Thus, for instance,as shown in FIG. 8(a), at position 2.29, LED 7 in bank 50 is driven witha 100% duty cycle while LEDs 2 and 3 in bank 48 are driven with 71% and29% duty cycles, respectively, that combine to yield a 100% value. Asthe position indicated by block 122 moves toward a position 3, the dutycycle in duty cycle box 2 decreases toward zero (i.e., fades off) whilethe duty cycle in duty cycle box 3 increases toward 100% (i.e., fadeson) until, at position 3, each of LEDs 3 and 7 had a 100% duty cyclewhile the other LEDs are off. Continuing, if the position is furthermoved toward a position 4, LED 3 in driven with 100% duty cycle whilethe duty cycle of LED 7 is reduced toward a zero value and the dutycycle of LED 8 is increased towards a 100% value. This process ofchanging LED duty cycles to steer or swivel the resulting illuminationpattern in front of a vehicle continues along the range of positions.

Referring now to FIG. 9(a), the position slider icon 120 is shown atposition 8 (see also block 122) at the right end of the range and theduty cycle boxes 1-10 indicate that LEDs 5 and 10 have a 100% duty cyclewhile the other LEDs are off. FIG. 9(b) shows the resulting illuminationpattern profile 80 c which is shown to the far left and which has asymmetrical pattern along its width.

Referring to FIG. 10(a), as the position slider icon 120 moves fromright to left, eventually the icon reaches a position 7.7 (see alsoblock 122). At this point, boxes 1-10 indicate that LED 5 is driven with100% duty cycle and LEDs 9 and 10 are driven with 30% and 70% dutycycles, respectively, while the balance of the LEDs are off. Referringalso to FIG. 10(b), illumination pattern profile 80 d results. Comparingthe patterns in FIGS. 9(b) and 10(b), it should be appreciated that asthe position changes from position 8 to position 7.7 the pattern startsto move from left to right as illustrated. More specifically, theintensity of a left portion of the profile decreases to fade out whilethe intensity of the right portion of the profile of 80 d increases andeffectively fades on.

Referring now to FIG. 11(a) position slider icon 120 has been movedfurther to the left to a position 7.4 (see also block 122). In thisposition, LED 5 is still driven with a 100% duty cycle while LEDs 9 and10 are now driven with 60% and 40% duty cycles, respectively.Illumination pattern profile 80 e results as shown in FIG. 11(b).Comparing the pattern profiles 80 d and 80 e in FIGS. 10(b) and 11(b),it can be seen that the left portion of the pattern continues todecrease in intensity while the right portion of the pattern continuesto increase in intensity further causing the pattern to appear to movein a smooth fashion from left to right as illustrated.

Referring now to FIG. 12(a), position icon 120 has been moved toposition 7, (see again block 122). At this point, LEDs 5 and 9 aredriven with 100% duty cycle while the balance of the LEDs are off. Theillumination pattern profile 80 f that results in shown in FIG. 12(b).Comparing the profiles 80 c and 80 f in FIGS. 9(b) and 12(b), it shouldbe appreciated that profile 80 c has moved from left to right as theposition has moved from position 8 to position 7. With the iterativepattern profiles as shown in FIGS. 10(b) and 11(b) and many otheriterative patterns therebetween, the transition from profile 80 c toprofile 80 f appears to be smooth and gradual to the human eye.

As the position is decreased from position 7, the pattern profilesgenerated by LEDs 1-10 are modified in a fashion similar to thatdescribed above thereby causing the pattern to effectively move in frontof a vehicle from one side to the other. As described above, andreferring again to FIGS. 8(a) and 8(b), eventually as a position valuedecreases, position 2.29 is reached where LEDs 2, 3 and 7 are drivenwith duty cycles of 71%, 29% and 100%, respectively, and illuminationprofile 80 b results. FIGS. 13(a) and 13(b) show LED duty cycles and theresulting illumination pattern profile 80 g at position 1.4 where thepattern profile 80 g is far to the right. Eventually, at position zero,the duty cycles and pattern profile 80 h shown in FIGS. 14(a) and 14(b)occur.

While the lighting system described above is described in the context ofvehicle headlights, it should be appreciated that various aspects of theembodiment may be used in other lighting systems to achieve similaruseful results. For example, a lighting system consistent with variousaspects of the system described above may be used in conjunction with alift truck or the like to provide light that can be steered to differentpositions along a vertical direction as opposed to a horizontaldirection. In this regard, see FIG. 15 that shows first and second lightmodules 42 and 44 arranged with module 42 vertically above module 44where the LEDs 1-5 and 6-10 are arranged to form vertical lines. Here,as shown, the modules 42 and 44 are arranged such that the illuminationfields F1-F10, respectively, corresponding LEDs 1-10 are interleaved ina fashion similar to that described above so that the dark space betweenfields generated by any two adjacent LEDs in one of the modules isilluminated by one of the LEDs in the other of the modules so that noabrupt changes in intensity occur across the resulting illuminationpattern profile. In the illustrated example in FIG. 15, field F7 isgenerated which overlaps fields F2 and F3 when LEDs 2, 3 and 7 are on.In addition, as above, in at least some embodiments it is contemplatedthat as the direction of the illumination pattern generated by the LEDs1-10 is changed, the duty cycles of the LEDs may be modified so thatmovement of the illumination pattern appears to be smooth between thevarious positions.

It has been recognized that, in addition to being able to generate asingle steerable illumination pattern, the system described above mayalso be used to generate a relatively wide bright illumination patternwith a dark spot where the dark spot is movable to different positionswithin the wider illumination pattern range in an adaptive fashion. Forexample, it may be that a wide bright illumination pattern is desirablein front of a vehicle but that the portion of the wide bright patterndirected toward an oncoming vehicle should be less intense or off. Tothis end, see FIG. 16(a) where a wide light profile is illustrated whichincludes a dark space between profile portions 80 i 1 and 80 i 2. Here,by adjusting LED duty cycles or on and off cycling in a controlledfashion, the dark spot between profile portions 80 i 1 and 80 i 2 can bemoved left and/or right and/or its width can be increased or decreasedas appropriate.

Referring again to FIG. 7, in at least some embodiments, to sense oncoming vehicles, additional sensors 112 of various types may beprovided. For example, at least one of the sensors 112 may be a twodimensional CCD or other camera sensor for obtaining images of the spacein front of a vehicle that are provided to processor 102. Processor 102may be programmed to analyze obtained images and identify vehicleswithin the camera's field of view. Based on the locations of vehicles inthe on-coming traffic, processor 102 may then control the LEDs 1-10 toadjust the position of the dark spot or to adjust positions of multipledark spots within the wider bright illumination pattern. When noon-coming traffic is sensed, as shown in FIG. 16(b), a wide brightillumination pattern 80 j may be generated by processor 102 where allLEDs 1-10 are completely on.

While the systems described above include only two light modules 42 and44, it should be appreciated that other embodiments may include three ormore light modules to further increase the intensity of the illuminationpatterns generated and/or to further increase the ability to generaterelatively smooth light patterns and enhance the illusion of smoothsteering of the resulting pattern. To this end, see FIG. 17 where fourlight modules 42, 44 1042 and 144 are shown arranged in a line and whereresulting overlapping illumination fields F1-F20 result. Here, processor102 (see again FIG. 7) would be controlled to change the on and off dutycycles of the various LEDs 1-20 in a controlled fashion to generatedesired illumination pattern profiles where a pattern profile issteerable or where a dark spot generated by a pattern profile issteerable in a fashion similar to that described above.

While each of the light modules (e.g., 42) described above includes asingle line of LEDs, in other embodiments modules with multiple rows ofLEDs are contemplated so that a resulting illumination pattern profilecan be steered both vertically and horizontally to at least some degree.In this regard see FIG. 18 where modules 150 and 152 each have threerows of five LEDs so that resulting illumination fields can havevertical as well as horizontal offsets as shown at 154. Here, the shapesof the lenses (not labeled) through which LED light travels may have tobe modified so that the fields align appropriately. In FIG. 18 exemplaryillumination patterns are shown in phantom at 156 and 158 where pattern156 is generated in an upper left-hand location within space 154 whilepattern 158 is smaller than pattern 156 and is generated in a lowerright-hand space of 154.

One or more specific embodiments of the present invention have beendescribed above. It should be appreciated that in the development of anysuch actual implementation, as in any engineering or design project,numerous implementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Thus, the invention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the invention asdefined by the following appended claims.

To apprise the public of the scope of this invention, the followingclaims are made:

What is claimed is:
 1. A method for steering a vehicle headlightillumination pattern wherein a headlight includes a plurality of LEDsarranged in a line and at least a first lens mounted adjacent the LEDsto direct light from each LED into an illumination field associated withthe LED, wherein the illumination fields of energized LEDs togethercreate an illumination pattern and wherein a first edge illuminationfield is at one end of the illumination pattern and a second edgeillumination field is at another end of the illumination patternopposite the one end, the method comprising the steps of: providing aprocessor programmed to perform the steps of: illuminating a subset ofconsecutive LEDs in the line including LEDs associated with the firstand second edge illumination fields; as the direction of vehicle wheelschanges: (i) fading the LED associated with one of the first and secondillumination fields off while simultaneously fading the LED associatedwith the other of the first and second illumination fields on therebychanging the illumination pattern; and (ii) repeating step (i) so thatthe illumination pattern tracks the direction of the vehicle wheels.